Electric incandescent lamp



Aug. i3, w46. E. G. DORGELO Er AL,

ELECTRIC INCANDESCENT LAMP Filed June 6, 1938 Patented Aug. 13, 1940UNITED sTATEs PATENT OFFICE 2,211,597 ELETRIC INCANDESCENT LAMPApplication June 6, 1938, Serial No. 212,178 In the Netherlands June 12,1937 8 Claims.

Our invention relates in general to electric incandescent lamps, andmore particularly to such lamps having a filament sealed within arelatively small envelope and which are designed to 5 operate at apressure "of more than one atmosphere. Still more particularly, ourinvention relates to lamps of the above type provided with means forcontrolling the location of the blackenlng of the bulb whereby theoperating life of l the lamp is materially increased.

It is a known fact that in an electric incandescent lamp the efficiency,in other words the emitted number of lumens per watt, increases the morethe temperature of the filament is raised. However, this automaticallycauses a more rapid vaporization of the filament. Since in a standardelectric incandescent lamp the life of the lamp is determined by theinstant at which the filament burns through, it will be evident that 20it is not possible in practice to improve the elciency of the lampwithout reducing the life of the lamp. The life of such a lamp is,therefore, determined by the time which it takes the f'llament to burnthrough. During the burning of 25 the lamp, Vaporization of the fllamentoccurs. The vaporized tungsten particles are deposited as a very thinlayer on the wall of the bulb body. However, because of the relativelylarge bulb surface of ordinary lamps, this layer is not detri- I mentalto the light emission even toward the end of the life of the lamp.

The conditions are materially different in an electric incandescent lampwith an operating pressure of more than 1 atmosphere. Such lamps 35 arepreferably designed with a bulb of which the internal volume isconsiderably smaller than further use, the filament, generally speaking,will p be still intact, and this is an indication that the 50 filament,during the burning life of the lamp,

could be loaded more highly without harmful results whereby a higherstarting economy can be obtained. 55 The electric incandescent lampaccording to In this the invention, which has an operating pressure ofmore than 1 atmosphere, contains an element which acts as a chimney,whereby a circulation of gas is formed when the lamp is in operation.Due to this gas circulation, the vaporized fila- 5 ment particles arecarried along by the gas current and are deposited on the bulb body atpoints at which they are not detrimental with respect to the lightemission. The element which acts as the chimney is, according to theinvention, preferably combined with means which retard the gas currentcreated in the lamp by the chimney effect. The filament particlescarried along in the gas current will thereby be given an even greateropportunity to be liberated from the gas current and to be deposited.

Partly because of this condition, the applicants have found that thelamp according to the invention can be designed with a maximum inter--nal diameter of less than mm. It will be evident that a bulb of ratherlarge dimensions might become dangerous to the surroundings because ofthe pressure in the bulb. By designing the lamp in accordance with theinvention, with the element acting as a chimney, and preferably incombination with the above-mentioned retarding means, it becomespossible to design the bulb with very small dimensions without.experiencing detrimental blackening results during the life of the lamp.When the operating pressure in the lamp according to the invention ismore than 9 atmospheres, the above-mentioned advantages are present to astill greater extent. In this case, the maximum internal diameter of thebulb body can even be selected so as not to exceed 15 mm.

As a result of the favorable action of the chimney and the retardingmeans which may be used, and also of the high pressure, the load of thefilament in the lamp according to the invention can be'selected higherthan in the customary lamps. It is recommended to select those values insuch a way that the efllciency of a new lamp is more than 12.5 lumensper watt and preferably more than 15 lumens per watt.

The applicants have found that it is particularly advantageous to havethe retarding means located between the chimney and the bulb wall. Theretarding means may be of widely different types. The walls of thechimney and/or of the bulb may, for instance, be made rough. It is alsopossible to form the retarding means of one or several constrictions inthe bulb body, or to design them as parts protruding from the chimney.Another possibility is to use a quantity of glass wool or quartz wool ora porous mass as the re- 55 tarding means. If desired, the chimneyitself may have a rather thick wall which is made porous, and in thatmanner serves as a retarding means. The chimney may also be madesomewhat conical. It is further possible to employ as the retardingmeans a wire which preferably is coiled once or several times and whichis placed around the chimney. It is also possible to let the inside wallof a helically coiled wire, placed against the bulb wall, serve as thechimney, while the turns will function as the retarding means. It isfurther possible, according to the invention, to form the filament ofsuch a shape that it functions as the chimney itself.

Further objects and advantages of our invention will appear from thefollowing description of species thereof and from the accompanyingdrawing, in which:

Fig. 1 is a longitudinal sectional view of an electric incandescent lampcomprising our invention, Fig. la being a similar view thereof on anenlarged scale, and Figs. 2, 3, 4 and 5 are similar views of variousmodifications of our invention.

Referring to Fig. 1, the lamp there shown is to operate at a voltage of220 volts and consists of a small tubular bulb or envelope I of quartzor hard glass which has a length of 40 mm. and on internal and outsidediameter of 6 and 9 mm. respectively. The said envelope I is filled witha suitable gas such as nitrogen, argon or krypton or mixtures thereof,as is well known in the art. The operating pressure in the lamp ispreferably 35 atmospheres or thereabouts while the efiiciency isapproximately 15 lumens per watt. A small tube 2 of quartz glass ismounted within the envelope I longitudinally of the same and slightlyabove a filament 3 of tungsten or other suitable material. The saidfilament is supported within the envelope I by conventional leading-inor current supply wires 3', 3 which are sealed into the end of thequartz envelope. The tube 2 of quartz serves as a chimney, an upward gasflow (as indicated by the arrows in the drawing) being formed in thischimney by the heat developed by the filament 3. This gas flow changesdirection when it arrives in the upper part of the lamp, and ows back tothe lower part of the lamp through the space 5 between the chimney andthe wall of the bulb. The filament material carried along by the gasflow is mainly released from such flow in the space 5 and ls depositedon the envelope I in the zone A where it is not detrimental to the lightemissions.

In the modification shown in Fig. 2, the lamp there illustrated issimilar to, and has substantially the same dimensions as, the lamp shownin Fig. 1. While the operating pressure again is 35 atmospheres, theefliciencyis somewhat higher. being approximately 20 lumens per watt. Aretarding means in the form of a quantity of glass wool I is placed inthe lamp in the space 5 between the chimney 2 and the inside wall of thebulb body. This retarding means acts to impede or retard the gas currentcreated in the lamp by the chimney 2. With such a retarding means, therelease of the vaporized filament material takes place in a still bettermanner than with a chirrmey alone, so that there will be less chance ofthe vaporized filament materials being deposited at points on the bulbbody at which it would be determinental to the light emission.

In the physical embodiment of the lamp according to Fig. 3, theretarding medium consists of a wire 8 helically coiled around thechimney 2, the windings of the wire functioning as the retardlng means.

In the modified form of lamp shown in Fig. 4, the chimney is formed bythe inside wall of a coil 9 placed against the inside wall of the bulbbody I. 'I'he rising gas flow passes upward through the imaginarycylindrical element which is defined by the inside portions of the coilturns. Above the coil 9, the gas ow then reverses its direction andflows back through the turns themselves which consequently act as theretarding means.

In Fig. 5, a physical embodiment of the lamp according to the inventionis illustrated in which the filament I0 is designed as a rather heavycoil so that an upward gas flow is formed within this coil. The desiredchimney effect is therefore produced by the filament itself.

The various forms of retarding means mentioned above can be mountedWithin the lamp envelope in any one of sereval different ways, it beingespecially convenient to locate such means on the leading-in wires 3',3' of the lamp. The chimney within the lamp may also be mounted indifferent ways. For instance, it is possible to suspend it from one orboth wires 3', 3' or to fasten itin the bulb body.

In the appended claims. the use of the expression high-pressureincandescent lamp" is to be considered as referring to lamps in whichthe operating pressure is higher than one atmosphere.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. A high-pressure electric incandescent lamp operating at an efficiencyin excess of 121/2 lumens per watt with a long useful life andcomprising a cylindrical envelope having a diameter of less than twentymillimeters and containing a gas filling, a filament sealed within saidenvelope, and chimney m'eans within said envelope extendinglongitudinally thereof and located above said filament when the lamp isin operation to thereby create a gas circulation within said envelope.

2. An electric incandescent lamp of the highpressure type operating atan efficiency in excess of' 121/2 lumens per watt comprising acylindrical envelope having a diameter of less than twenty millimetersand containing a gas filling, a filament sealed within said envelope,chimney means within said envelope extending longitudinally thereof andlocated above said filament when the lamp is in operation to therebycreate a gas circulation Within said envelope. and retarding meansWithin said envelope and disposed above said filament and in thedownward path of said gas circulation to thereby impede the same.

3. An electric incandescent lamp of the highpressure type operating atan eiliciency in excess of 121/2 lumens per watt comprising acylindrical envelope having a diameter of less than twenty millimetersand containing a gas filling, a fllament sealed within said envelope,chimney means within said envelope extending longitudinally thereof andspaced from the walls thereof, said chimney means being located abovesaid filament when the lamp is in operation to thereby create a gascirculation within said envelope. and retarding means arranged in thespace between said chimney means and the Wall of said envelope tothereby impede the downward iiow of the gas circulation created by saidchimney means.

4. An electric incandescent lamp comprising an envelope containing a.gas filling, a. filament sealed within said envelope, chimney meanswithin said envelope and spacedi'rom the walls thereof, said chimneymeans being located above said filament when the lamp is in operation tothereby create a gas circulation within said envelope, and retardingmeans arranged in the space between said chimney means and the wall ofsaid envelope to thereby impede the downward flow of the gas circulationcreated by said chimney means, said retarding means comprising aquantity of loosely arranged illamentary vitreous material.

5. An electric incandescent lamp comprising an envelope containing a gaslling, a lament sealed within said envelope, chimney means within saidenvelope and spaced from the walls thereof, said chimney means beinglocated above said lament when the lamp is in operation to therebycreate a gas circulation within said envelope, and retarding meansarranged in the space between said chimney means and the wall of saidenvelope to thereby impede the downward ow of the gas circulationcreated by said chimney means, said retarding means comprising a porousmass.

6. An electric incandescent lamp of the highpressure type operating atan efficiency in excess of 121/2 lumens per watt comprising acylindrical envelope having a diameter of less than twenty millimetersand containing a gas filling, a lament sealed within said envelope,chimney means within said envelope extending longitudinally thereof andspaced from the walls thereof, said ,chimney means being located abovesaid lament when the lamp is in operation to thereby create a gascirculation within said envelope, and retarding means arranged in thespace between said chimney means and the wall of said envelope tothereby impede the downward ow of the gas circulation created by saidchimney means, said retarding means comprising a coil of wiresurrounding said chimney means.

7. An electric incandescent lamp of the highpressure'type operating atan eciency in excess of 121/2 lumens per Watt comprising a cylindricalenvelope having a diameter of less than twenty millimeters andcontaining a gas lling, a lament sealed within said envelope,v 'chimneymeans within said envelope extending longitudinally thereof and spacedfrom the walls thereof, said chimney means being located above saidlament when the lamp is in operation to thereby create a gas circulationwithin said envelope, and retarding means within said envelope to impedethe downward ilow of the gas circulation created by said chimney means,said retarding means comprising one or more obstructions located" neymeans, said retarding means comprising a quantity of loosely arrangedlamentary ma terial.

EDUARD G. DORGELO. WILLEM ELENBAAS. HENDRICUS J LEMJMENS. MARINUS J.JANSEN.

